I built a cage like I would for tommatoes and covered it with clear plastic and put it over one of are small trees, it is like 5 or so feet tall. Then I took 4 stakes and put one north, east, south, and west about 6 feet from the cage and tied string from the cage to the stakes, this will stop it from blowing over in strong winter winds. The plastic will let heat come in and stay in. If I where you I would also put like 6 inches of leaves in the bottom too, o yeah, dont make the cage to big or it wont hold heat as easy. Good luck :D